Fan

ABSTRACT

Examples are disclosed herein that relate to fans for cooling systems. One example provides a device including an impingement surface, and a fan positioned to direct a flow of air onto the impingement surface. The fan comprises an impeller and motor assembly, and a housing comprising an inlet end, an outlet end, and a side extending at least partially between the inlet end and the outlet end. The fan further comprises a strut located to position the impeller and motor assembly relative to the housing, and an opening formed in the side of the housing, the opening comprising an upstream edge located farther from the impingement surface than a downstream edge of the housing along an axial direction of the fan.

BACKGROUND

Cooling fans may be used in many different types of devices, includingbut not limited to electronic systems such as computing devices. Coolingfans may help to dissipate heat produced by a device and thus tomaintain temperatures of device components.

SUMMARY

Examples are disclosed herein that relate to fans for cooling systems.One example provides a device including an impingement surface, and afan positioned to direct a flow of air onto the impingement surface. Thefan comprises an impeller and motor assembly, and a housing comprisingan inlet end, an outlet end, and a side extending at least partiallybetween the inlet end and the outlet end. The fan further comprises astrut located to position the impeller and motor assembly relative tothe housing, and an opening formed in the side of the housing, theopening comprising an upstream edge located farther from the impingementsurface than a downstream edge of the housing along an axial directionof the fan.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block diagram of an example device including a fanpositioned to direct a flow of air onto an impingement surface.

FIG. 2 shows a perspective view of an example fan.

FIG. 3 shows a side view of the example fan of FIG. 2.

FIG. 4 shows a view of an outlet end of the example fan of FIG. 2 alongan axial direction of the fan.

FIG. 5 shows a perspective view of another example fan.

FIG. 6 shows a perspective view of another example fan.

FIG. 7 shows a perspective view of another example fan.

FIG. 8 shows a schematic view of another example fan.

DETAILED DESCRIPTION

Cooling fans may be located near an impingement surface of a heattransfer component (e.g. a heat sink) of a device to help move airacross the impingement surface and thus dissipate heat produced by thedevice, as mentioned above. Cooling fans for electronic devices may beimplemented in various forms, such as axial fans and centrifugalblowers. An axial fan moves air in a direction from an inlet to anoutlet along an axis of rotation of the impeller of the fan, while ablower moves air in a radial and/or tangential direction relative tothis axis. Blowers and axial fans may offer different performancecharacteristics. For example, blowers may create a higher pressure headat the same volume of airflow compared to a comparable axial fan, butalso may create more acoustic noise and may occupy more space.

An axial fan may occupy less space and operate more quietly than ablower, and thus may be more suitable for use than a blower in systemswhere less acoustic noise is desired, such as a system with microphones.Some axial fan may take the form of box fans, where a housing enclosesand supports the motor and impeller. When an axial box fan is placedinto a system with limited space in an axial direction (e.g. in adirection along an axis of rotation of the fan impeller), the fan intakemay be restricted by near field vent patterns, which may impede theability of the fan to supply flow. In such a fan, the struts thatconnect an impeller and motor assembly of the fan to the housing may belocated approximately flush with a downstream edge of the housing. Thismay allow the struts to be positioned within the housing such that theaxial fan may be mounted flush to a wall, plenum, and/or vent withoutairflow recirculating from the fan outtake to the fan intake.

Instead of box fans, some axial fans may be implemented as housinglessfans. A housingless fan may reduce system impedance associated with therestriction of airflow into a housing, and thus allow more airflowcompared to a comparable box fan in some use environments. However, theuse of a housingless axial fan also may involve the use of fan supportstructures that occupy additional space compared to an axial box fan.Further, a housingless fan may generate undesired recirculation of airfrom the downstream to the upstream side of the fan.

Accordingly, examples are disclosed that relate to an axial fan housingwith one or more openings formed in the housing that may facilitate airflow through a cooling system relative to a comparable axial fan lackingsuch openings. The disclosed examples may provide for convenientmounting in an electronic device compared to a housingless fan, yet alsoprovide for lower impedance in spatially limited systems than acomparable box fan without such openings. As described in more detailbelow, the openings in the housing may be formed such that an upstreamedge (upstream with reference to the direction of airflow, e.g. closerto an inlet than an outlet of the fan) of an opening is located fartherfrom an impingement surface than at least a portion of a downstream edge(downstream with reference to the direction of airflow, closer to theoutlet than the inlet of the fan) of the housing. Further, in someexamples, the upstream edge of an opening may be located farther from animpingement surface than a downstream edge of a fan impeller, while inother examples, an opening may have any other suitable spatialrelationship with a downstream edge of an impeller. The use of openingsas described herein may help to achieve a larger hydraulic diameter forthe flow path exiting an axial fan compared to a similar fan withoutsuch openings. Such openings also may help to utilize the swirl(tangential) and radial components of the airflow exiting the fanblades, which may be otherwise restricted by a housing without suchopenings.

FIG. 1 shows a block diagram of an example device 100 comprising anaxial fan 102 and an impingement surface 104 located to receive a flowof air from the axial fan 102. Air, indicated by arrows, 106 flows fromthe inlet side 108 of axial fan 102, through the fan, and towardimpingement surface 104. Air then flows across impingement surface 104,thereby removing heat from the impingement surface. The impingementsurface may have fins or other geometrical features that increases thesurface area, which may increase a rate of heat transfer compared to theuse of an impingement surface lacking such features. It will beunderstood that device 100 may represent any suitable device. Examplesinclude, but are not limited to, computing devices such as mobilecomputing systems (e.g. laptop computers), desktop computers,entertainment computers (e.g. video game consoles), and sensor systems(e.g. imaging and/or acoustic sensing systems, including but not limitedto depth imaging and/or microphone array systems).

Axial fan 102 comprises a housing having an opening 112 formed in a sideof the housing. As mentioned above, such a configuration may help tolower flow impedance of the cooling system of device 100 relative to asimilar axial fan lacking such an opening. FIGS. 2 and 3 show onenon-limiting example of an axial fan 200 suitable for use as axial fan102. Axial fan 200 comprises a housing 202 including an outlet end 204,an inlet end 206, and a plurality of sides (one of which is shown asside 208) extending at least partially between the inlet end 206 and theoutlet end 204. Axial fan 200 further includes an impeller and motorassembly 209 comprising an impeller 210 with a plurality of blades and amotor configured to drive movement of the impeller 210. Each impellerblade has an upstream edge 214 (upstream along a direction of airflow)and a downstream edge 216 (downstream along a direction of airflow). Theupstream edge and downstream edge of the impeller blades may be referredto herein as the upstream and downstream edge of the impeller,respectively. Axial fan 200 further includes a plurality of struts 218located to position the impeller and motor assembly relative to thehousing 202. While the depicted embodiment includes three struts, itwill be understood that any suitable number of struts having anysuitable configuration may be used.

The axial fan 200 also includes an opening 222 formed in a side of thehousing 202. The opening 222 comprises an upstream edge 224 locatedfarther from the outlet end 204 of the axial fan 200 than a downstreamedge 220 of the housing 202. In some examples, struts or otherstructures of an axial fan may extend farther downstream along the axialdirection (along axis 229) than the downstream edge of the housing,while in other examples the downstream edges of the struts or otherstructures may be approximately flush with, or upstream of, thedownstream edge of the housing, such that the downstream edge of thehousing is the most downstream portion of the fan.

The housing and opening or openings may have any suitable configuration.In the example of FIG. 2, housing 202 has a generally squarecross-sectional shape in a direction transverse to the axial direction.In other examples, a housing may have a different cross-sectional shape,such as another polygonal shape, an elliptical shape (e.g. circular),etc. It will be understood that a shape of a fan may be designed orotherwise selected based upon a configuration of a device in which thefan is to be used and how the fan is to be secured within the device.

The depicted openings take the form of cutaway portions of thedownstream portion of the housing that extend fully to a downstream edgeof the housing along an axial direction, as shown at 230 in FIG. 3,wherein the term “cutaway” does not imply any particular method offorming the openings in the housing. In other examples, an opening maytake the form of a hole formed in a side of the housing, such that theopening does not extend fully to the downstream edge of the housing.

Each opening may extend any suitable length along the axial direction ofthe fan. As a non-limiting example, an opening may have a depth of20-30% of the housing depth in the axial direction from the downstreamedge of the housing. Such an opening may allow a 10-90% increase inoperating flow in some use environments. In other examples, an openingmay extend up to 50% of the axial depth of the housing from thedownstream edge of the housing, or even farther. An axial depth of anopening may be constrained by unwanted recirculation of air and/oracoustic noise, which may be system-specific parameters. It will beunderstood that these specific examples are presented for the purpose ofillustration, and are not intended to be limiting in any manner, as anysuitable number and configuration of openings may be used to achievedesired flow characteristics in a system.

An opening may have any suitable depth relative to an impeller. Forexample, an opening may be configured such that the upstream edge of theopening is located farther from a downstream edge of a housing than atleast a portion of a downstream edges of an impeller. In otherimplementations, an upstream edge of an opening may be located atapproximately a same distance from an outlet end of the housing as adownstream edge of an impeller, or closer to a downstream edge of ahousing than a downstream edge of an impeller.

As mentioned above, in an electronic device, an axial fan may be placedto direct a flow of air against an impingement surface to cool anelectronic component. As such, when located in a device, the upstreamedge of the opening of the housing is located farther from theimpingement surface than the downstream edge of the housing, and may befarther from the impingement surface than at least a portion of thedownstream edge of the impeller in some examples.

FIG. 4 shows a view of the outlet end of the example axial fan of FIG. 2as viewed along an axial direction of the fan, and illustrates exampleconfigurations of the struts and impeller. In this example, the strutsextend from the housing 202 to a support 226 for the impeller and motorassembly 209 in a curved shape. The shape and contour of the struts maybe designed to help reduce flow impedance, and allow air to flow intothe impingement surface with a suitably low pressure drop across thefan. The shape and contour of the struts may also be designed to lessenany acoustic noise generated due to the interaction of the struts withthe impeller and/or the downstream edge of the impeller. As examples,the struts may be designed to have a suitably low effect on impedance(e.g. not be a bluff body), to shape and/or turn airflow in a suitabledirection for an intended end use, and/or limit an acoustic interactionbetween the blades and struts as the blades pass the struts. Further,the strut shape may be configured to increase an effectiveness ofdirecting the airflow to and along the impingement surface, such as bydirecting airflow along a channel direction of any fins on theimpingement surface. A strut may meet the housing at any suitablelocation, including at a corner or along an edge of the housing. Threestruts are shown in the example of FIG. 4, but any suitable number ofstruts may be used.

FIG. 5 shows another example axial fan 500. Like fan 200, fan 500comprises a housing 502 having a square cross section transverse to anaxial direction. However, fan 500 comprises four struts 518 that connectto the housing 502 at corners of the housing. Further, struts 518 have astraight, rather than curved, configuration. Additionally, fan 500includes four openings 522 (e.g. an opening on each side of the fanhousing), whereas fan 200 includes two openings.

FIG. 6 shows yet another example implementation of an axial fan 600.Like fan 500, fan 600 has a square cross-sectional shape transverse toan axial direction, but has openings 622 formed in a first subset ofsides (e.g. side 608 plus the opposite side) and not formed in a secondsubset of sides (e.g. side 618 plus the opposite side. In yet otherexamples, openings may be on adjacent sides, rather than opposite sides,and on any other suitable subset of sides than that shown.

FIG. 7 shows another example implementation of an axial fan 700. Unlikefans 200, 500, and 600, fan 700 comprises a housing 702 having anelliptical cross-section transverse to an axial direction of the fan.Fan 700 also includes a plurality of openings 722 formed in the side708.

FIG. 8 shows another example implementation of an axial fan 800. Unlikefans 200, 500, 600, and 700, fan 800 omits struts that position animpeller and motor assembly relative to a housing. Instead, fan 800includes a housing with one or more walls 802 that may be mounted toother structures within a device incorporating the fan. Further, themotor and impeller assembly 808 of fan 800 may be mounted to animpingement surface 806. The walls 802 and motor and impeller assembly808 may be positioned such that walls 802 do not extend fully to thedownstream edge 804 of the fan.

Another example provides a device comprising an impingement surface, anda fan positioned to direct a flow of air onto the impingement surface,the fan comprising an impeller and motor assembly, a housing comprisingan inlet end, an outlet end, and a side extending at least partiallybetween the inlet end and the outlet end, a strut located to positionthe impeller and motor assembly relative to the housing, and an openingformed in the side of the housing, the opening comprising an upstreamedge located farther from the impingement surface than a downstream edgeof the housing along an axial direction of the fan. The device mayalternatively or additionally include the upstream edge of the openingbeing located farther from the impingement surface than a downstreamedge of the impeller. The device also may alternatively or additionallyinclude a housing comprising a polygonal transverse cross-section and aplurality of sides, wherein the opening in the side is a first openingin a first side, and wherein the housing comprises one or more otheropenings formed in one or more sides other than the first side. Thedevice also may alternatively or additionally include a housingcomprising openings formed in a first subset of sides and not formed ina second subset of sides. The device also may alternatively oradditionally include a housing comprising an elliptical cross-sectiontransverse to the axial direction. The device also may comprise an axialfan. Any or all of the above-described examples may be combined in anysuitable manner in various implementations.

Another example provides a fan comprising an impeller and motorassembly, a housing comprising an inlet end, an outlet end, and a sideextending at least partially between the inlet end and the outlet end, astrut located to position the impeller and motor assembly relative tothe housing, and an opening formed in the side of the housing, theopening comprising an upstream edge located farther from the outlet endof the fan along an axial direction of the fan than a downstream edge ofthe housing. The fan may alternatively or additionally include theupstream edge of the opening being located farther from the outlet endthan a downstream edge of the impeller. The fan may alternatively oradditionally include a housing comprising a polygonal transversecross-section and a plurality of sides, wherein the opening in the sideis a first opening in a first side, and wherein the housing comprisesone or more other openings formed in one or more sides other than thefirst side. The fan also may alternatively or additionally include ahousing comprising openings formed in a first subset of sides and notformed in a second subset of sides. The fan also may alternatively oradditionally include a housing comprising an elliptical cross-sectiontransverse to the axial direction. The fan also may alternatively oradditionally comprise an axial fan. Any or all of the above-describedexamples may be combined in any suitable manner in variousimplementations.

Another example provides a computing device, comprising an impingementsurface, and a fan positioned to direct a flow of air onto theimpingement surface, the fan comprising an impeller and motor assemblyincluding an impeller having a downstream edge, a housing comprising aninlet end, an outlet end, and a side extending at least partiallybetween the inlet end and the outlet end, a strut located to positionthe impeller and motor assembly relative to the housing, and an openingformed in the side of the housing, the opening comprising an upstreamedge located farther from an impingement surface than a downstream edgeof the impeller along an axial direction of fan. The computing devicemay alternatively or additionally include a housing comprising apolygonal transverse cross-section and a plurality of sides, wherein theopening in the side is a first opening in a first side, and wherein thehousing comprises one or more other openings formed in one or more sidesother than the first side. The computing device also may alternativelyor additionally include a housing comprising openings formed in a firstsubset of sides and not formed in a second subset of sides. Thecomputing device also may alternatively or additionally include ahousing comprising an elliptical cross-section transverse to the axialdirection. The computing device also may alternatively or additionallyinclude a fan comprising an axial fan. Any or all of the above-describedexamples may be combined in any suitable manner in variousimplementations.

It will be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The subject matter of thepresent disclosure includes all novel and nonobvious combinations andsubcombinations of the various processes, systems and configurations,and other features, functions, acts, and/or properties disclosed herein,as well as any and all equivalents thereof.

1. A device comprising: an impingement surface; and a fan positioned todirect a flow of air onto the impingement surface, the fan comprising animpeller and motor assembly, a housing comprising an inlet end, anoutlet end, and a side extending at least partially between the inletend and the outlet end, a strut located to position the impeller andmotor assembly relative to the housing, and an opening formed in theside of the housing, the opening comprising an upstream edge locatedfarther from the impingement surface than a downstream edge of thehousing along an axial direction of the fan.
 2. The device of claim 1,wherein the upstream edge of the opening is located farther from theimpingement surface than a downstream edge of the impeller.
 3. Thedevice of claim 1, wherein the housing comprises a polygonal transversecross-section and a plurality of sides.
 4. The device of claim 3,wherein the opening in the side is a first opening in a first side, andwherein the housing comprises one or more other openings formed in oneor more sides other than the first side.
 5. The device of claim 3,wherein the housing comprises openings formed in a first subset of sidesand not formed in a second subset of sides.
 6. The device of claim 1,wherein the housing comprises an elliptical cross-section transverse tothe axial direction.
 7. The device of claim 1, wherein the fan comprisesan axial fan.
 8. A fan, comprising: an impeller and motor assembly; ahousing comprising an inlet end, an outlet end, and a side extending atleast partially between the inlet end and the outlet end; a strutlocated to position the impeller and motor assembly relative to thehousing; and an opening formed in the side of the housing, the openingcomprising an upstream edge located farther from the outlet end of thefan along an axial direction of the fan than a downstream edge of thehousing.
 9. The fan of claim 8, wherein the upstream edge of the openingis farther from the outlet end than a downstream edge of the impeller.10. The fan of claim 8, wherein the housing comprises a polygonaltransverse cross-section and a plurality of sides.
 11. The fan of claim10, wherein the opening in the side is a first opening in a first side,and wherein the housing comprises one or more other openings formed inone or more sides other than the first side.
 12. The fan of claim 10,wherein the housing comprises openings formed in a first subset of sidesand not formed in a second subset of sides.
 13. The fan of claim 8,wherein the housing comprises an elliptical transverse cross-section.14. The fan of claim 8, wherein the fan comprises an axial fan.
 15. Acomputing device, comprising: an impingement surface; and a fanpositioned to direct a flow of air onto the impingement surface, the fancomprising an impeller and motor assembly including an impeller having atrailing edge, a housing comprising an inlet end, an outlet end, and aside extending at least partially between the inlet end and the outletend, a strut located to position the impeller and motor assemblyrelative to the housing, and an opening formed in the side of thehousing, the opening comprising an upstream edge located farther from animpingement surface than a downstream edge of the impeller along anaxial direction of fan.
 16. The computing device of claim 15, whereinthe housing comprises a polygonal transverse cross-section and aplurality of sides.
 17. The computing device of claim 16, wherein theopening in the side is a first opening in a first side, and wherein thehousing comprises one or more other openings formed in one or more sidesother than the first side.
 18. The computing device of claim 16, whereinthe housing comprises openings formed in a first subset of sides and notformed in a second subset of sides.
 19. The computing device of claim15, wherein the housing comprises an elliptical transversecross-section.
 20. The computing device of claim 15, wherein the fancomprises an axial fan.